Improve <textarea> validation performance.

Improve <textarea> validation performance.

HTMLTextAreaElement::value() is a costly operation, and we can avoid it
if a <textarea> has neither 'required' attribute nor 'maxlength' attribute.

This CL improves PerformanceTests/DOM/textarea-dom.html and
textarea-edit.html by a few percent.

BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181785

[tkent, 2014-09-09 22:42:33]

Patchset #1 (id:1) has been deleted

[tkent, 2014-09-09 22:42:46]

Patchset #1 (id:1) has been deleted

[tkent, 2014-09-09 23:49:36]

tkent@chromium.org changed reviewers:
+ keishi@chromium.org

[tkent, 2014-09-09 23:49:37]

Please review this.

[keishi, 2014-09-11 03:04:03]

lgtm

[tkent, 2014-09-11 03:04:37]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2014-09-11 03:05:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/543403003/20001

[commit-bot: I haz the power, 2014-09-11 03:08:10]

Committed patchset #1 (id:20001) as 181785